This invention relates to shock absorber systems for use in the wheels of inline skates and other small-wheeled transport devices.
While inline skating has enjoyed significant success, with current technology, an almost perfectly smooth pavement is still required to fully enjoy this activity. This has limited inline skating to well-maintained parks and recreational areas. Roads that feel perfectly comfortable to users on cars and bikes leave inline skaters shaken and frustrated.
One reason for this problem is that existing inline skates do not contain any shock absorbing system, relying only on the elasticity of the tire on each wheel to perform this function. While a number of shock absorbing systems have been proposed over the years for inline skates, these have involved modifying the skate itself by adding heavy and bulky springs, dampers, and the like to the skate truck or frame. However, none of these systems are currently being commercially used, primarily because the weight and complexity they add to the skate are not offset by the advantages they provide. The reliance on tire resiliency to absorb road variations also is disadvantageous in that it requires the use of tires which have some softness and resiliency, for example a durometer in the 65-75 range. However, such softer tires result in more tire deformation as it contacts the road surface, requiring the user to exert more energy, and thus limiting the speed attainable with the skate. A harder tire, for example a tire with a durometer in the 85-100, range would provide a faster skate, while requiring the use of less energy by the skater. The absence of an effective shock absorber system on inline skates also results in vibration passing into a user""s feet and legs; even on relatively smooth pavements, these vibrations contribute to skater fatigue over time.
Problems similar to those described above exist for other transport devices, particularly ones having small wheels similar to those of inline skates. Such transport devices could include scooters, street skis, some skateboards, and the like.
A need therefore exists for an improved shock absorbing system for use in inline skates and related transportation devices which does not result in any appreciable increase in either weight or bulk for the device, and is relatively simple and inexpensive, while still being capable of absorbing a substantial portion of road vibration without reliance on the tires of the wheels, so as to facilitate a smoother ride on all surfaces while permitting harder, faster tires to be utilized.
In accordance with the above, this invention provides an inline skate or related transportation device having a plurality of wheels, each of which includes a non-rotating hub inside a rotating tire, with the hub for at least one of the wheels having a shock absorber therein. For preferred embodiments, all of the wheels of the skate or other device have the shock absorber either formed or mounted therein. For preferred embodiments, each of the hubs has an axle passing therethrough, and each shock absorber includes an outer tube and an elastomer, preferably a low durometer elastomer, between the outer tube and the axle. The outer tube may have an array of holes formed in at least a portion thereof which the elastomer may partially pass through. The sizes of the holes in the outer tube may be selected to achieve a desired stiffness for the shock absorber. The shock absorber also preferably includes an inner tube through which the axle passes, the elastomer being sandwiched between the inner and outer tubes.
For preferred embodiments, the shock absorber includes a mechanism which inhibits movement in rotational degrees of freedom and at least reduces movement in all translational degrees of freedom except vertical, there being a reduced stiffness for the shock absorbers in the vertical degree of freedom. To achieve this objective, the elastomer may be mounted within a flexural mechanism, flexure for such mechanism having minimum stiffness in the vertical direction. A replaceable tire may also be provided on each wheel, which tire is preferably of an ultra-hard material.
The invention also includes a wheel for an inline skate or other small wheeled transport device which includes a shock absorber positioned in its hub. The shock absorber may for example include an elastomer, preferably a low durometer elastomer, positioned between an outer tube of the shock absorber and an axial channel of the hub. Holes may be formed in at least a portion of the outer tube, as indicated above, and an inner tube in the axial channel may also be provided, the elastomer being sandwiched between the inner and outer tubes. The shock absorber may also include a mechanism which inhibits movement in rotational degrees of freedom and at least significantly reduces movement in all translational degrees of freedom except vertical, there being a reduced stiffness for the shock absorber in the vertical degree of freedom, the elastomer for example being mounted within a flexure assembly of the type indicated above. The outer tube may also have a shoulder at each end thereof, with a roller bearing being mounted on each shoulder, the hub being attached to the shock absorber through the bearings. The wheel may also include a replaceable tire, which tire preferably has an ultra-hard outer layer of a plastic material over a core of an even harder plastic material. The outer and inner layers of the tire preferably have different appearances so that wear through of the outer layer may be easily seen. The tire may be sufficiently elastic to be fitted over a rotatable rim portion of the wheel, or a two-part rim may be provided along with components for normally holding the two parts together with the tire mounted thereon, the components permitting separation of the parts for tire replacement.
The invention also includes a hub mounted shock absorber of the type indicated above which, at a minimum, includes an outer tube with an elastomer, preferably a low durometer elastomer, mounted in the tube and having an axial channel formed therethrough. A hole array may be formed in the outer tube, as indicated above, and an inner tube may also be provided in the axial channel, as may the mechanism indicated above which inhibits movement in rotational degrees of freedom and at least significantly reduces movement in all translational degrees of freedom except vertical.
Finally, the invention includes a replaceable tire for an inline skate wheel, or wheel of another small-wheeled transportation device, which tire includes an ultra-hard outer layer of a plastic material over a core of an even harder plastic material, which materials may have a different appearance.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings, common elements having the same reference numeral in each of the drawings.